Their final push comes as Nato leaders meet in Chicago this weekend to discuss winding down the Afghan war. They will also have time to reflect on the cost of a decade of combat – 3,000 Nato troops killed (414 of them British, nearly 2,000 American), thousands more Afghans dead, and an estimated financial debt of more than half a trillion dollars.

In Chicago the talk may be one of withdrawal and mission accomplished, but in Ghazni, like in much of Afghanistan, the war is still being hard fought and it remains unclear how much long-lasting progress has been made.

The Daily Telegraph is the first newspaper to accompany the 82nd Airborne as it tries to clear southern Ghazni of insurgents while bolstering the Afghan army, police and administration. Ghazni, south-west of the capital, sits on the country's main road linking Kabul and Kandahar.

As men and money have poured into Helmand and Kandahar with Barack Obama's troop surge, this province has been neglected and security has plummeted, local MPs complain.

The familiar ingredients of weak governance from Kabul, resentment at official corruption and the proximity of Taliban safe havens in Pakistan have all accelerated the decline.

By last year, Taliban fighters had congregated in southern Ghazni and came to control all but the town centres of many districts. Their shadow government of courts, governors and judges, which has been disrupted in Kandahar and the south, has grown strong here, MPs say.

An under-strength force of fewer than 1,000 Poles with a mission to secure the highway was unable to halt the slide and local people complained the force had been largely pushed back to its base.

The highway, the economic link between the country's main cities, remained perilous to Nato and Afghan forces and was often hit by bombs and mines. Insurgents based in Pakistan regularly use the province as a corridor to reach Kabul or Kandahar.

The American paratroopers, from Fort Bragg in North Carolina, have just six months to turn the situation around before they hand over to Afghan forces.

"We have an opportunity, but we know we have a limited opportunity because we know that this fall, or late this fall, we are going to see the first significant fall in troops," said Col Mark Stock, overall commander of the paratroopers.

In the six weeks since their arrival seven paratroopers have been killed, mainly by huge homemade bombs planted in the roads. Their strategy is to push off the main highway and into the surrounding villages where Taliban fighters rest, hide weapons, and stage attacks on the road with impunity.

As they widen a bubble of security around the road and district centres they will leave Afghan soldiers and police in checkpoints and bases to guard the gains. But they realise that their enemy will not only be the Taliban, but also time.

Lt Col Rob Salome, commander of the brigade's "Red Devils" battalion stationed in Muqur district, said: "In my mind we have been given a very short amount of time to make a big difference. If you only fight them on Highway One, you are doing exactly what they want you to do. They know where you are and they have freedom to move. We need to take away that impunity and doing that we take away their freedom."

Capt Ling and his paratroopers were dropped in the early hours of Monday last week on just such an operation.

In the desert in Muqur district several miles from the road, their job was to provide security for engineers clearing and securing the main Nawa road. With the helicopters gone, the men set off across the scrubby desert, weaving between unseen tents of sleeping nomads, the only sound the crunch of their boots and the distant barking of dogs.

When first light came, they were asleep in the vineyards of their destination, the village of Musa Kheyl. As the village's menfolk hurried to prayer, wrapped in shawls against the dawn chill, they were surprised to see US and Afghan soldiers patrolling their streets for the first time.

Lt Abdul Majid, the commander of the Afghan soldiers with the Americans, rounded up the men in front of the mosque and began to explain that they were there to bring security.

His speech was watched with a mixture of interest, resignation and the occasional flash of defiance. The Americans took the names of each man, then scanned his eyes and took his picture to see if he was in a database of wanted insurgents.

"Of course we are happy that they are here, because they want to bring security," said a young man called Mohammad Omar. "It has been very bad here. There are sometimes Taliban who come here and disturb the villages and ask for food."

Sidiqullah, another young man, was more reserved. "Some people say it's good the Americans are here, but others want them to leave the country," he said.

As the mission and days wore on, it became clear the Taliban had melted away in the face of overwhelming force.

Villagers became friendlier and began to offer the Afghan soldiers food and tea, while curious young boys came out to stare at the paratroopers.

Everywhere the story was similar. The Taliban were feared and disliked, but the Afghan government was also distrusted. One boy and girl said their parents had been killed by the Taliban two months ago because their father had worked in the Afghan army.

"There's been no reconstruction in Ghazni and no one has done anything for the people yet," said Lt Majid, who has been in the province for two years.

After three days when Capt Ling and his men returned to base, they had had only one small firefight with no casualties on either side. The Nawa road had been cleared of five mines and an army and police post were under construction.

The strength of the Afghan police and army will be key to any success the 82nd Airborne has when it leaves. The Americans fear that although well-trained and enthusiastic, the new local forces may well be cut off. Orders sent to Kabul for food, ammunition and support have in the past disappeared into a black hole.

Lt Majid has similar concerns. "We will be ready to take over security," he said. "But only if the Americans can give us the resources and the weapons."